This paper analyzes the secrecy performance of a reconfigurable intelligent surface (RIS) assisted wireless communication system with a friendly jammer in the presence of an eavesdropper. The friendly jammer enhances the secrecy by introducing artificial noise towards the eavesdropper without degrading the reception at the destination. Approximate secrecy outage probability (SOP) is derived in closed form. We also provide a simpler approximate closed-form expression for the SOP in order to understand the effect of system parameters on the performance and to find the optimal power allocation for the transmitter and jammer. The optimal transmit and jamming power allocation factor is derived by minimizing the SOP assuming a total power constraint. It is shown that the SOP performance is significantly improved by the introduction of the jammer and a gain of approximately 3 dB is achieved at an SOP of 10–4by optimally allocating power compared to the case of equal power allocation.
This paper analyzes the secrecy performance of a reconfigurable intelligent surface (RIS) assisted wireless communication system with a friendly jammer in the presence of an eavesdropper. The friendly jammer enhances the secrecy by introducing artificial noise towards the eavesdropper without degrading the reception at the destination. Approximate secrecy outage probability (SOP) is derived in closed form. We also provide a simpler approximate closed-form expression for the SOP in order to understand the effect of system parameters on the performance and to find the optimal power allocation for the transmitter and jammer. The optimal transmit and jamming power allocation factor is derived by minimizing the SOP assuming a total power constraint. It is shown that the SOP performance is significantly improved by the introduction of the jammer and a gain of approximately 3 dB is achieved at an SOP of 10–4by optimally allocating power compared to the case of equal power allocation.
This paper evaluates the physical layer security performance of a reconfigurable intelligent surface (RIS) enabled wireless network in the presence of a passive eavesdropper. To secure the information transmission, a cooperative jammer is proposed to generate interference signal that degrade the performance of the eavesdropper. The source-to-RIS and RIS-to-destination links are subjected to Rician and Rayliegh fading distributions with phase errors, respectively, while other transmission links in the network follow the Nakagami-m fading distributions. The system phase error of the RIS is estimated by the von Mises distribution. To quantify the secrecy performance of the concerned system, the exact closed-form expressions in terms of connection outage probability (COP), security outage probability (SOP), and secrecy throughput (ST) are derived. In addition, the asymptotic expression of the system COP is obtained at high signal-to-noise ratio (SNR), providing more insight about the system performance. The accuracy of the derived expression is justified by Monte Carlo simulation. Also, the results clarify the analysis of the security performance, taking into account the impact of system and channel parameters on the system.
In this paper, we analyze the physical layer security of a jamming-aided wireless communication system assisted by a reconfigurable intelligent surface (RIS). Our setup consists of a source node communicating with a destination node with the help of a RIS, and under the presence of a malicious passive eavesdropper attempting to overhear the genuine transmission. Furthermore, an external cooperative jammer is incorporated to reinforce the system’s secrecy by broadcasting an artificial noise to disrupt the eavesdropper; such a noise can be removed at the destination. Finally, we assume that the tunable RIS phases based on the channel estimates are subject to quantization errors. By virtue of the well-adopted Gamma and Exponential distributions approximations, an approximate expression for the system’s intercept probability (IP) is derived in terms of the main setup parameters. The results show that the greater the number of reflective elements (REs) and jamming power, the better the secrecy, while the number of quantization bits has less impact when exceeding 3 bits. In particular, an IP of 10−3can be reached with 50 REs even when the legitimate link’s average signal-to-noise ratio (SNR) is 15 dB below the wiretap channel’s average SNR. Monte Carlo simulations endorse the derived analytical results.
This paper addressed the optimal design of signal with artificial noise in Reconfigurable Intelligent Surface (RIS) assisted physical secure communication system, which becomes complicated due to the introduction of an auxiliary and reconfigurable communication link. We firstly formulate the optimal form design of the transmitted signal and artificial noise (AN) as a problem of maximizing secrecy capacity under the constraint of secrecy outage probability (SOP). By constructing an equivalent channel for RIS-assisted communication scenario, the optimal solution is derived which involves transmit direction vector, transmit power vector and power splitting factor. The results can provide guidance for the secure transmission design of confidential communication systems in consumer Internet of Things (CIoT) scenarios.
This paper studies the secrecy rate maximization problem of a secure wireless communication system in the presence of multiple eavesdroppers. The security of the communication link is enhanced through cooperative jamming with the help of multiple jammers. First, a feasibility condition is derived to achieve a positive secrecy rate at the destination. Then, we solve the original secrecy rate maximization problem, which is not convex in terms of power allocation at the jammers. To circumvent this nonconvexity, the achievable secrecy rate is approximated for a given power allocation at the jammers, and the approximated problem is formulated into a geometric programming one. Based on this approximation, an iterative algorithm has been developed to obtain the optimal power allocation at the jammers. Next, we provide a bisection approach, based on 1-D search, to validate the optimality of the proposed algorithm. In addition, by assuming Rayleigh fading, the secrecy outage probability (SOP) of the proposed cooperative jamming scheme is analyzed. More specifically, a single-integral form expression for the SOP is derived for the most general case, as well as a closed-form expression for the special case of two cooperative jammers and one eavesdropper. Simulation results have been provided to validate the convergence and the optimality of the proposed algorithm, as well as the theoretical derivations of the presented SOP analysis.
This article delves into the optimal design of transmitting signals with artificial noise (AN) in reconfigurable intelligent surface (RIS) assisted secure communication system. Due to the introducing of RIS, injecting AN into null space of Alice-Bob channel is not optimal. Our approach commences with the formulation of the signal and AN design as an optimization problem, with the objective of maximizing the secrecy rate while conforming to the secrecy outage probability (SOP) constraint. Through constructing an equivalent channel model for the RIS-assisted communication scenario, we deduce the optimal solution which is represented as transmitting direction and corresponding power allocation for both information-bearing signal and AN. The research results contribute a theoretical objective for the practical design of AN transmission scheme in RIS-assited secure communication scenarios.
Abstract This paper investigates a cooperative beamforming (BF) and jamming schemes in active reconfigurable intelligent surface (RIS)-assisted secure communication network, where an active RIS perform reflecting BF and a friendly jammer transmits jamming signal to enhance the security. Specifically, we consider a secrecy rate maximization problem under specific power constraints by assuming that perfect channel state information (CSI) of the eavesdroppers (Eves) can be obtained by the transmitter (Alice). Using the semidefinite relaxation (SDR) and CharnesCooper transformation, we address this problem by performing a one-dimensional search which involves solving a sequence of semidefinite programs (SDPs). For more practical scenario that perfect CSI of the Eves can not be obtained by Alice, a robust joint design of BF and jamming is proposed and the worst-case secrecy rate optimization is solved by using the S-procedure and its extension. Finally, simulation results demonstrate the performance gains of the proposed designs.